I have a tired 366 Chevy big block in one of my trucks. I have a fresh rebuilt 454 out of a motor home. I have heard that a 366 and 454 flywheel have the same weights on the flywheel and are inter changeable but no one I talk to is sure 100%. Lots of experience with 427's and 454's but not a lot with a 366. Trying to get out of buying a new flywheel.